The Northern Waterthrush is a large and brownish wood warbler, not a
thrush, rarely seen far from water in the forests of North America.
It is often shy and hard to approach and spends most of its time
walking on the ground. Ornithologist E.H. Forbush’s statement over a
half century ago still applies: “It is a large wood warbler
disguised as a thrush and exhibiting an extreme fondness for water.”
It has a wide distribution from the northeastern U.S., Canada,
including central and northern B.C., Montana and Alaska. It winters
in Mexico, northern South America and the West Indies.

Identification:

General: This is a rather heavy-bodied, short-tailed, large
warbler. The bill is fairly long and heavy, with a slightly decurved
culmen. Length: 14-17 cm. Weight: 18 g.

Adult Male: Generally dark brown above (varying in shade from
cold gray-brown to warmer olive-brown) and whitish to sulphur yellow
below. Throat, breast and sides are streaked in black and these
streaks are sharply defined. Wings and tail are unmarked and dark
brown. White to sulphur yellow supercilium is of even width,
attenuated behind the eye. Leg colour varies but are usually light
brownish.

Adult Female: Males and females are identical in plumage but
males are slightly larger in size. There is no significant seasonal
variation.

Juvenile: Wings and tail as in adults but median and greater
wing-coverts tipped with buff forming two narrow bands across wing;
superciliary stripe less distinct than adult. Streaking much less
sharply defined than in adults.

Similar Species: The Louisiana Waterthrush is best
distinguished from the Northern by a broader, bolder and whiter
supercilium, especially at the rear of the supercilium. It also has
buffy flanks, and white breast with sparser brownish streaking. It
has pink legs, which during spring, tend to be brighter pink looking
like bubble gum legs. The Louisiana is also slightly larger than the
Northern and its range is mostly east of the Mississippi River in
the U.S.

Behaviour: The Northern Waterthrush combines a distinctive
walking gait with bobbing of its tail and rear portion of its body.
It will bob its tail almost continually in an up-and-down motion. It
spends most of its time walking on the ground, although it will walk
along tree limbs, some of which may be at a sharply sloping angle.
It will continue to bob when flushed up onto a limb.
Their flight is swift and low.

Waterthrushes forage deliberately on the ground where there is damp
leaf litter or shallow water, turning over leaves with the bill,
gleaning invertebrate prey form the undersides of leaves or the
ground under them.

Singing birds will perch well above the ground on horizontal limbs,
and even from treetops in stunted forests in the northern most parts
of their breeding range.
Nests are located on or near the ground, often among the root system
of a fallen tree, at the base of a standing tree, or set into a
stream bank. The nest is a cup composed of stems, pine needles, and
leaves and lined with moss stalks, rootlets and fibers. There are 4
to 5 off white eggs, marked with browns and purplish-gray.

Conservation:

In ranking of Neotropical migrants for conservation priorities on a
scale of 1 to 8, the Northern Waterthrush ranks number 8, based on
its wide breeding and wintering ranges.

Capture Rates

Not rare, but relatively uncommon to Colony Farms, the
Northern Waterthrush is a breeding bird of northern interior
forests. They generally frequent wooded areas that include
water and are therefore not readily seen directly in the
banding area. Capture rates (2010-2012; standardized as
birds captured per 100 net hours) concentrated in August and
September reflect dispersal of these long distance migrants
to their wintering grounds.